Tetrahedron letters

A synthesis of (−)-tashiromine and formal synthesis of (+)-tashiromine utilizing a highly enantioselective pyrrole/cobaloxime π-cation cyclization

JL Gage, BP Branchaud

Index: Gage, Jennifer L.; Branchaud, Bruce P. Tetrahedron Letters, 1997 , vol. 38, # 40 p. 7007 - 7010

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Citation Number: 49

Abstract

Cyclization of (5-N-pyrrolyl-2-hydroxypentyl) cobaloxime (13) proceeds by intramolecular electrophilic aromatic substitution of a cobaloxime π-cation onto the pyrrole ring to provide 6- exo cyclization product (14) in 95% yield. This cyclization is highly enantioselective. It is applied to a synthesis of highly enantioenriched (−)-tashiromine,(−)-21, and a formal synthesis of (+)-tashiromine.